You know that feeling when you open a vendor invoice and the first thing you do is check for a typo?
I've heard that story a few times this year alone. Each time from a technical founder or CTO. Each time it sounds the same: "we started with Retool because it was fast, now we're paying $60,000 a year for 120 seats and we can't dig ourselves out". One of the companies in our Catch The Tornado portfolio had exactly this problem last quarter.
I'm not writing this to trash Retool. It's a great tool — at a specific moment in a company's life. The problem is that this moment lasts shorter than people think.
How I Know What I'm Talking About
I'm Tomasz Karwatka. I co-founded Divante (exit at $65M), Vue Storefront/Alokai (Y Combinator, $40M Series A), Callstack, and Open Loyalty. With my brother Piotr at Catch The Tornado, we've invested in over 40 companies, including ElevenLabs.
Across 20 years in enterprise software, I've seen every approach to "let's build internal tools faster". Access. Filemaker. Microsoft Power Apps. Appsmith. Budibase. And finally Retool, which won this category — fairly, because it's the most polished product of the bunch.
But winning the "low-code internal tools" category is not the same as winning the "operating system of your company" category.
What Retool Actually Does Well
I'll start with what I like, because this isn't going to be a hater post.
Time to first dashboard. In Retool, you build a CRUD panel for a database in 30 minutes. Drag-and-drop, query builder, and you have a working admin for a Postgres table. No TypeScript framework can touch that.
Connectors. 150+ integrations out of the box — Stripe, Salesforce, Snowflake, every popular database. You don't have to write a GitHub API client to build a PR dashboard.
UI components. A rich library of ready-made components. Tables, forms, charts, calendars. They look OK, they work OK.
Retool Workflows and Retool AI. Zapier-style automations, plus LLM integration. As an add-on to the core product — reasonable.
If your use case is "show 5 tables to the ops team so they don't click around raw Postgres" — Retool is great and don't overthink it.
Where the Pain Begins
Retool is brilliant for the first 6 months. Then one of three things starts to happen, and I've seen all three many times.
Pain #1: per-seat pricing. Retool Business costs $50 per user per month (Retool pricing, as of 2026). You have 100 people in ops clicking through your tools? That's $60,000 a year. For tools you built yourself. Retool isn't adding any business value here — it's just counting heads.
At Divante we had 500 people and we ran exactly this calculation. It turned out that building our own system in 6 months pays back within a year and is free afterwards. That's the math that eventually landed in Open Mercato.
Pain #2: the complexity ceiling. Simple CRUDs fly in Retool. But when your workflow has 15 steps, multi-level business conditions, orchestration across several systems, and integration with your own rules engine — you start writing JavaScript in tiny popup windows, debugging someone else's runtime, and praying nothing breaks in production. You quickly discover that what you saved at the start, you give back in maintenance.
Pain #3: vendor lock-in with harder cement. Retool keeps your apps in their format. You can't easily export them to React. Business logic lives inside their runtime. When you want to migrate — it turns out "migration" means "rewrite everything from scratch".
I met a fintech CTO who put it like this: "I have 80 apps in Retool and I know that one day I'll have to rewrite all of it. Every quarter I delay that decision means 10 more apps to rewrite".
Open Mercato — A Different Philosophy
Open Mercato is not an alternative to Retool in the sense of "same thing, but cheaper". It's a completely different product category.
Retool is a low-code builder — you click UI, write a little JavaScript, get an app running in their runtime.
Open Mercato is a TypeScript framework — Next.js, React, PostgreSQL, MikroORM, Redis, Zod. You write code, get an app you host yourself, and it's 100% yours.
Sounds like more work? Initially, yes. But Open Mercato gives you out of the box what you'd have to either give up or bolt on externally with Retool:
These aren't mocks. It's 15+ production modules with 1,000+ unit tests.
The Comparison You Came For
I know that's why you're here, so here's the table:
Why the Overlay Pattern Matters Here
The biggest hidden difference between Retool and Open Mercato is about how you introduce changes, not how you build the first app.
In Retool, customization means writing JS in small windows. When Retool updates the runtime, your logic can behave differently. The contract between "core" and "your code" practically doesn't exist.
In Open Mercato we applied the Open-Closed Principle literally. All your code lives in the Overlay layer. You never touch core.
// Override the pricing engine. Core stays untouched.
import { PricingService } from '@open-mercato/sales';
export class MyPricingService extends PricingService {
calculate(item: CatalogItem, ctx: PricingContext): Money {
return this.applyCustomRules(item, ctx);
}
}
// Register in the Awilix DI container — done.
// Pull the latest Open Mercato release — zero merge conflicts.
Same on the frontend. Page Override swaps out a page without forking. Widget Injection injects an element from one module into another. Scaffolding generates a CRUD in seconds.
In practice: your business code never blocks a platform upgrade. That's something Retool by definition cannot deliver — because there, core isn't yours.
AI-Native — And Why It's Not Just Marketing
Everyone writes "AI-powered" on everything now. I get the skepticism. But the difference here is concrete and measurable.
Retool AI runs in their environment, with their context, on their models. You get suggestions in their editor. It's OK, but it's a black box.
Open Mercato is built so that your AI agent (Claude Code, Cursor, Copilot) can reliably extend it:
In practice, a feature that takes 4 hours in Retool gets generated by an agent in 30 minutes — and the output is TypeScript code with Playwright tests that lives in your own Git.
When to Pick Retool (Honestly)
I'm not going to pretend Open Mercato beats Retool on every axis. Retool wins when:
If that's your world — take Retool, don't overcomplicate. Seriously.
When Retool Is the Wrong Choice
Retool becomes an expensive trap when:
In these scenarios Retool isn't even a bad choice. It's simply the wrong tool category.
A One-Page Decision Framework
Here's the simple matrix I use when I advise founders. Take a sheet of paper and answer honestly:
If three or more answers point you toward Open Mercato — Retool is too small a spoon for you.
What to Do Tomorrow
Two concrete things.
If you're on Retool and feel it starting to pinch: run a 30-minute audit. Calculate your actual annual cost per seat, count how many apps you have in Retool, how many are core business, how many are one-offs. Usually 10–20% of the apps deliver 80% of the value — those are the ones worth rewriting first.
If you're planning a new internal tools project: instead of opening Retool by default, clone Open Mercato and see what spins up in 5 minutes.
git clone https://github.com/open-mercato/open-mercato.git
cd open-mercato
npm install
npm run dev
Five minutes to a running CRM/ERP. Then you build the part that actually makes a difference — your business logic.
The repo is here. If you think the market needs this kind of alternative, drop a star :)